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    <title>数据类型判断typeof及call</title>
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Object.prototype.toString.call('')
"[object String]"
typeof ''
"string"

Object.prototype.toString.call({})
"[object Object]"
typeof {}
"object"

Object.prototype.toString.call(null)
"[object Null]"
typeof null
"object"

({}).toString.call(null)
({}).toString.apply(null)
"[object Null]"
typeof null
"object"

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